Epitope tagging has become an important tool for detecting, localizing and purifying expressed recombinant proteins (Nygren et al., Trends Biotechnol. 12: 184-188 (1994)). This methodology involves the fusion of the tag amino acid sequence to the amino or carboxy terminus of a protein of interest, and then identifying the tag with a monoclonal antibody (mAb). For most biochemical applications, the use of epitope tags eliminates the need to generate an antibody to the specific protein that is to be detected and/or purified.
Currently, there are several validated mAb epitopes in wide use for protein tagging, including the FLAG peptide epitope (8 amino acid residues reactive to mAbs M1 and M2) (Hopp et al., BioTechnology 6: 1204-1210 (1988)), the V5 epitope (14 amino acids found in the P and V proteins of paramyxovirus, Simian Virus 5) (Southern et al., J Gen Virol. 72: 1551-1557 (1991)), the myc epitope (10 amino acids derived from the c-myc proto-oncogene product) (Evan et al., Mol. Cell. Biol. 5: 3610-3616 (1985)), the HA epitope (9 amino acids from the hemagglutinin of influenza virus) (Wilson et al., Cell 37(3):7 67-778 (1984)), and the 6×His epitope (Lindner et al., BioTechniques 22(1): 140-149 (1997)).
However, the choice of an epitope tag depends on the application, because not all tags and in particular the corresponding mAbs are equally suitable for all immunodetection methods, e.g. Western blotting, immunofluorescence staining, immunoprecipitation, and flow cytometry. Accordingly, there is a need in the art for novel detection tags and the antibodies recognizing those detection tags.